Natural Order and Science

[Harris]

All objects of experience are characterized by generic and specific properties. Ponder over this question:

Why the form of a material thing became the manner in which material particles combined, with their relationship giving rise to the specific properties of the material thing?

I don't know what objects of experience are, I don't know what it means when you say ""Why the form of a material thing became the manner in which material particles combined."

Think like this. Why humans do not have tails like monkeys do, why palms are not giving strawberries, why everything maintain a specific shape and properties?

I think Aristotle was the person who first attempt to describe this unseen factor by using the term SOURCE OF UNITY.

“The role of the form in determining the persistence of an organism results from its role as the SOURCE OF UNITY. The form, including the organism’s vital functions, makes a heap of material constituents into a single organism.”

(Metaphysics VII 16)

So, what is the origin of this SOURCE OF UNITY (I say it a Code or Instructions) that holds the elements of anything into a specific order?